Bark and sapwood water storage and the atypical pattern of recharge and discharge of water reservoirs indicate low vulnerability to drought in Araucaria araucana.

This article focuses on the role of internal water storage in the stem tissues—specifically the inner bark and sapwood—of Araucaria araucana, a conifer native to southern Andean forests, during dry season conditions. The study found that A. araucana’s unusually thick inner bark, with high water content and capacitance, along with the sapwood, contributes significantly (5–11%) to daily transpiration by releasing stored water in the afternoon to buffer water deficits. An atypical diurnal pattern was observed where stem water content and diameter increased in the morning, linked to an osmotic gradient driving water from sapwood to inner bark, and decreased in the afternoon as water was discharged to support transpiration. These findings suggest that the species’ internal water storage and efficient hydraulic system help maintain favorable water status during drought, indicating that drought alone may not explain recent crown desiccation, which could involve other factors such as pathogens.